Silage corn harvest may be two weeks early this year in much of Wisconsin and possibly Minnesota, says Joe Lauer, University of Wisconsin extension corn agronomist.

For silage chopping, he says to be ready to harvest 42-47 days after silking. “That’s the first indication of when some of these custom operations might need to be taking place,” Lauer says. Silking, which usually occurs about two days after tasseling, is easily observed during windshield surveys.

Growers and custom operators should watch silage corn fields for silking, add 42-47 days (half-milk-line stage of maturity) and adjust their harvest schedules accordingly.

“A lot of it hinges on the silking date of corn. Usually, corn leaf development prior to silking is quite variable and driven by heat and environment. But the grain-filling period is much more driven by just days. In other words, when corn is silking, you know that you have about 55-60 days before corn will be mature.”

“A couple of things conspired this year to really push the crop along for us here in Wisconsin,” Lauer says. Most growers planted within a week and a lot of corn was planted very early. “The combination of early and somewhat aggressive planting and an outstanding May and June have really contributed towards early growth.”

As of July 5, growing degree units (GDU) were about 200-300 GDUs ahead of normal, he adds. “This time of year we’re collecting about 25-30 GDU’s per day. So that means we’re probably at least 10-13 days ahead of normal. We’ll probably have corn tasseling the week after July 4 across most of Wisconsin.”

The state, as well as Minnesota, is dry, however, he warns. “That does affect things a little. All bets are off as to what’s going to happen if you have a lot of stress.”